1. Field of the Invention
The invention relates to a navigation device, and more particularly, to a navigation device that adjusts a navigation route when detecting that a passenger has fallen asleep.
2. Description of the Prior Art
Global Positioning System (GPS) based navigation devices are well known and are widely employed as in-car navigation devices. Common functions of a navigation device include providing a map database for generating navigation instructions that are then shown on a display of the navigation device. These navigation devices are often mounted on or in the dashboard of a vehicle using a suction mount or other mounting means.
The term “navigation device” refers to a device that enables a user to navigate to a pre-defined destination. The device may have an internal system for receiving location data, such as a GPS receiver, or may merely be connectable to a receiver that can receive location data. The device may compute a route itself, or communicate with a remote server that computes the route and provides navigation information to the device, or a hybrid device in which the device itself and a remote server both play a role in the route computation process. Portable GPS navigation devices are not permanently integrated into a vehicle but instead are devices that can readily be mounted in or otherwise used inside a vehicle. Generally (but not necessarily), they are fully self-contained—i.e. include an internal GPS antenna, navigation software and maps and can hence plot and display a route to be taken. The navigation devices can either be personal navigation devices such as GPS devices or mobile phones that contain the functionality of GPS receivers and navigation software.
When a passenger rides in a vehicle, it is very common for the passenger to fall asleep due to the relaxed state that the passenger enters due to sitting still for a long period of time in the vehicle and due to the motion of the vehicle as the vehicle travels over roads. Often times, the driver of the vehicle may wish to let the sleeping passenger continue to sleep rather than take a chance on the passenger waking up earlier than necessary. In situations like these, the driver may wish to travel on a longer route that is more conducive to letting the passenger continue to sleep rather than traveling on the quickest route that may not be as conducive to letting the passenger sleep. For example, if a parent of an infant is driving a vehicle with the infant as a passenger, the parent may want to let the infant continue to sleep longer rather than waking the infant up earlier than necessary.
Unfortunately, most of the time navigation devices will guide drivers to travel on the quickest route to reach a destination. While the quickest route is usually what most drivers wish to follow, drivers traveling with a sleeping passenger may be willing to delay their arrival at the destination if a longer, and at the same time, smoother and quieter route more conducive to sleeping can be followed instead of the quickest route. Currently drivers must think of and navigate to the longer, smoother, and quieter route on their own, and the navigation device is not able to help drivers conveniently find alternate routes when a passenger is sleeping.